To support the specific aims of the Projects in this application, the Murine Hematopathology Core will: 1. Provide gross pathology/autopsy service for murine models described in the Projects of the program. 2. Perform standard histological, immunohistochemical, and histochemical stains necessary to evaluate pathologic findings in murine models of aplastic anemia and leukemia. 3. Interpret the pathologic findings and render diagnoses. 4. Develop new paraffin-based immunohistochemical stains to improve the evaluation of disease phenotypes and the signaling events that underlie their pathogenesis. 5. Provide photographic services to document representative pathologic findings. In providing these services, the Core will interact directly with Projects.